Marine invertebrates have been identified by chemists as likely sources of new biomedical substances. Pharmacologists, physiologists and biochemists have demonstrated that many of these novel marine products modify fundamental life processes in ways suggesting biomedical applications. These molecules can serve as leads to guide the pharmaceutical and chemical industries in developing new products. By determining the chemical structures and, eventually, the biochemical pathways by which these compounds are produced and the environmental or physiological triggers controlling their production, techniques of enhanced commercial production can be developed. The task of piecing together the structues of complex, biomediclally important, unknown natural products has benefited significantly from the development of mass spectrometry techniques. Mass spectrometry is among the most powerful tools for the determination of molecular structure. This technique is particularly suitable for the structure elucidation of naturally occurring compounds, especially those that are structurally novel. Clearly, the application of mass spectrometry to the structure elucidation of naturally occurring and/or biologically important marine compounds will lead to ground-breaking discoveries in marine chemistry, pharmacology and biotechnology thus providing essential help that the pharmaceutical industry needs in its efforts to cure intractable forms of cancer, inflammation, arthritis and viral infections.